This study examines the effect of different cap management techniques on the chemical and sensory qualities of Merlot wine. Merlot grapes were harvested on the same day and split into 3 separate 1-ton T bins with three different treatments: 2 punchdowns per day, 4 punchdowns per day, and 2 pumpovers per day. The timing between 2 punchdowns and pumpovers were approximately 5-8 hours apart, and the timing between 4 punchdowns was approximately 1-2 hours apart. Increasing punchdowns and pumpovers increased the pH (5% and 22% lower proton concentration, respectively) and pumpovers slightly decreased TA. The treatments also increased the volatile acidity and increased the sulfur dioxide binding capacity of the wine. Increasing the number of punchdowns had the greatest impact on color, catechin, and tannin accumulation, although pumpovers slightly increased this as well. Anthocyanins were decreased by the treatments, especially with the 4 punchdown treatment. Overall, these wines were not perceived to be very different from each other. The 2 Punchdown wine seemed to be slightly more preferred than the rest of the treatments, but this was a weak preference. Descriptive analysis from both tastings suggest that the 2 Punchdown wine may have been slightly lower in Astringency, Bitterness, Body, and Herbaceous/Green character. However, if so then this was a very weak trend.
Four Merlot wines were made with varying cap management regimes (all wines were destemmed): 2 punchdowns per day, 4 punchdowns per day, 2 punchdowns per day in addition to being crushed, and 2 pumpovers per day. There were no real chemical, phenolic, or microbial differences between treatments except that the wine with pumpovers had slightly higher volatile acidity. People tended to prefer the wine made from crushed grapes with two punchdowns per day.
Two merlot wines from identical lots of grapes were separated so that one received 3 weeks of extended maceration while the other was immediately pressed after alcoholic fermentation. There were no chemical differences between these wines, with a slight increase in VA in the extended maceration. The extended maceration wine had more tannin but less anthocyanin, and slightly more browning. Microbial presence was the same between wines. There were no significant sensory differences or preferences between wines.
Two different Merlot clones (181 and 343) were evaluated for chemical and sensory differences due to cold soaking. Not much color difference was observed between wines that had undergone cold soak compared to controls. However, significant sensory differences existed between wines, with most people preferring cold soaked wines.